Process of making citrate soluble phosphates.



UNTTED STATES PATENT GEErcE.

WILHELM WOLTERS, OF- MAGDEBURG-BUCKAU, GERMANY.

PROCESS OF MAKlNG CITRATE SOLUBLE PHOSPHATES.

SPECIFICATION forming part Of Letters Patent NO. 721,489, dated February 24, 1903.

Application filed February 11.1898.

T0 alt whom it may concern:

Be it known that I, WILHELM WoLTEEs, a subject of the Grand Duke of Brunswick, residing at Magdeburg-Buckau, Kingdom of Prussia, German Empire, have invented certain new and useful Improvements in Artificial Manure, of which the following is a specification.

This invention relates to improvements in the manufacture of artificial nianures, and has for its object the con version of phosphates of calcium, such as phosphorites and bone materials, into a state in which they are most efficient in promoting the development and growth of plants.

The new process for converting the phosphorites into compounds which are entirely citrate soluble consists in melting together the silicates of the alkaline earths and of the alkalies with phosphorite at a high temperature, not less than 1,200 centigrade. With the potassium compounds White heat must be employed, and with the soda compounds yellow heat may suftice. Thus compounds of the phosphor-silicic acid with the alkalies and the alkaline earths are produced which are completely soluble, in the well-known Wagner citrate solution. Analysis of the compounds has shown a content of 15.38 per cent. of'phosphoric acid, of which 15.28 per cent. is citrate soluble phosphoric acid, and, furthermore, 15.14 per cent. (citrate soluble) potassa.

In working the new process the phosphorite or bone material is melted with the silicates of the alkalies and of the alkaline earths. The silicate of alkali employed may be in the form of glass fragments or it may be produced from the alkali salts such as found in Stassfurt, or sulfate of soda and sand may be employed. If the silicates of the alkaline earths are used alone, the phosphorites will be rendered far less soluble than if the si1i-.

cates of the alkalies and the alkaline earths are used together. Furthermore, in using the silicates of the alkaline earths alone the process of rendering the compound soluble cannot be worked without loss of phosphoric acid. The double silicate of phosphor-silicic acid in which both groups of the bases are contained is far more easily worked than the one which contains bases of the alkaline Serial No. 669,996- (No specimens.)

earths alone. Only by using the twonamed bodies simultaneously .the high citrate solubility without any loss of phosphoric acid is obtained.

The proportions of the ingredients willdependupon the quality of the phosphorites employed. With'phosphorites of high percentage a suitable proportion of mixture will be one hundred parts, by weight, ofcphosphorite, sixty parts, by weight, of silicate of alkaline earths, and thirty parts, by weight, of silicate of alkali. If instead of'silicate of soda silicate of potassium isused-as, for instance, in using the Stassfurt salts of potassiumthe proportion of the silicate of the alkali may be somewhat increased. Small fluctuations in the composition are of no great consequence. If, however, a considerable amount of magnesia is present, the addition of silicic acid has to be somewhat reduced. In using glass fragments the desired proportions of silicic acid and bases may be obtained by the addition of carbonate of lime.

The citrate soluble compound will be formed at a high temperature only, at not less than 1,200 centigrade, it being abso lutely necessary that said temperature ,be suffioiently high to reduce the ingredients to a molten mass. If silicate of sodium is employed, a yellow heat will be sufficient. If silicate of potassium is employed, a White heat must be reached.

In working the process ovens such as the Well-known Siemens ovensmay be employed the bottoms of whichmay be formed of ma terials containing phosphoric acid.

The following furtherexample of the mixture has been used with most satisfactory re- I sults, in which the product after being completely fluxed has been found to be ninetynine per cent. soluble in a weak citrate solution:' one hundred parts of phosphorites,

eighty parts of chalk, eighty-four parts of silicate.

Iclaim as my invention.

1. The herein-described process of manu facturing citrate soluble phosphates by heating a mixture of natural phosphates, silicates of the alkalies and silicates of the alkaline earths to a temperature of not less than 1,200 centigrade atwhich the said materials are converted intoahomogeneous mass of a fluid phosphorite, about eighty parts of chalk,

molten state which when cold is perfectly eighty-four parts of silicate toatemperature soluble in citrate solutions. at which the mixture becomes a thin fluid 2. The herein-described processof manumolten mass.

facturing citrate soluble phosphates by heat- In testimony that I claim the foregoing as ing a mixture of phosphorite, chalk and silil my invention I have signed my name in prescates to a temperature of not less than 1,200 ence of two subscribing witnesses. centigrade at which the mixture becomes a thin fluid molten mass.

3. The herein-described process of manufacturing citrate soluble phosphates by heating a mixture of about one hundred parts of 1 WILHELM WOLTERS.

Witnesses:

MARGARET DIEDERIOH, JULIA ALICE WOLTERS. 

